Boat propulsion apparatus



KA f f 'ff Sept A. RONNING BOAT PROPULSION `APPARA'IUS Filed April 15. 1938 lNvENToR ATTORNEY HD'OLPH BONN/N6' Patented Sept. 3, 1940 UNITED STATES PATENT OFFICE BOAT PRoPULsIoN APPARATUS vAdolph Ronning, Minneapolis, Minn, l Application April 15, 193s, serial No. 202,258

i (Cl. 11s-17) Claims.

This invention relates generally to improvements in outboard motors such as used for the propulsion of water craft of various kinds. A

These motors derive their name from the fact 6 that they are supported in an Aoutboard fashion from the rear or other portion of the boat, and they conventionally embody an internal combustion motor equipped with a mounting bracket for supporting it upon the boat and with its 10 power shaft depended to a transmission unit which operates below thewater level and drives the propeller in the water. The engine is cooled by the circulationrof water through asuitableA jacket .and this watergis conveniently and logically obtained directly from the body of water in which the boat is operated. The water is cirf culated around the heated parts and is then dischargedand replaced by cool water so that `the circulation is in a constant stream with no recirculation whatever required 'I'he cooling Vwater is ordinarily forced through the cooling system by a water p'umpdriven in some manner lby the' motor; and, inasmuch as th'ewater is picked up and discharged below the water level in which the boat is operating, both the water rounding, the propeller so that the volatile gases will be broken up very nely and the noise more lo efficiently absorbed and eliminated.

' A further object is to provide a motor assem- ,f bly of the kind in which no mechanical` water f pump need be used, thus preventing damage by freezing, and in which the enclosing ho'usingl `parts of the transmission unit are eifectively j streamlined to reduce water resistance and drag to a minimum, and sloped to have a rudder effect to facilitate steering. n

Another object is to provide an attachment 20 for a conventional transmission unit and enclosed.

water circulating system, by the use of which the exhaust gases may be carried out throu h `the propeller hub as, and for the purposes, d

inlet and outlet and the circulating pump is ordinarily located in the transmission uhit aforesaid; Also associated with the transmission unit is the exhaust means for the motor which is desirably 80 arrangedv to discharge'the exhaust gases'below the water level in order to reduce the exhaust noises of the mptor.

- My invention particularly provides improve' scribed, and which attachment is so formed and 25 arranged that it will offer very littleresistance to travel through the Water.

Still a, further object is to provide blower means assembled in the propeller .hub and so arranged that the exhaust gases will be forcibly drawn from the engine by action of the propeller, and which blower means serves to discharge the gases outwardly and rearwardly along the axis of rotation of the propeller to thus` reduce noise in the provide a cooperating assembly and means where- Another object 4is to provide meas whereby 45 the exhausted gases and discharged cooling water are caused to be ejected through thehub portion ofthe propeller in a rearward direction substantially along theaxis of rotation of the propeller. As a result there occurs a very con- 50 siderableF outward suction atthe point of egress of the gases and water such that they will be forcibly drawn from the motor. 'I'hs suction isbrought about by the action of the propeller in the water by which itsl blades tend to urge manner hereinbefore set out.v -This structure thus provides both. an actual power suction as well as the pulling eifect of thevacuum vbehind the propeller upon the exhaust gases.

, The foregoing and other more specific objects of my invention,`to'gether with means whereby the 40 same -maybe 'carried' into eiect, will be made kind by the use of which attachment -the exhaust 5'5 thewater outwardlyA and rearwardly, causing at v- .gases may be carried out throughthe propeller over an opening Fig.3 is an enlarged cross section along the line 3-3 in Fig. 2.

Fig. 4 is a fragmental sectional elevation of a propeller having interior suction blades designed for use in the assembly of Fig. 2, for drawing the exhaust gases out through the hub of 'the propeller.

Referring now with more particularity to the drawings, the reference character A designates the motorwhich may be of any conventional type and which includes the depended tubular standard or member B journaled at C in a bracket' D by whichv the motor is supported in outboard thus be oscillated about a vertical axis on the bracket D by manipulation of the handle E, and the bracket is so arranged that it permits tilting adjustment and movement of the water in usual manner and forusual purposes. For convenience in this description, however, it will be assumed that the motor is operated with the standard BV vertically disposed and depended into the water.

Afixed to the lower end of this standard B by the clamp F is the transmission unit G, and the drive shaft H of the motor depends through the standard B into this unit G for the purpose of driving the propeller shaft J which is horizontally disposed aft direction. The actual driving connection is made through bevel gears K and, of course, the shafts H and J are suitably journaled in bearings L and are provided with oil seals M so that the chamber N may be oil ll'ed to lubricate the parts'. A conventional water pump O is arranged in the unit G and includes a piston P which is reciprocated by the cam Q on the propeller shaft J andoperates to draw in water at R and discharge it at S intol a tube T which carries it to the motor A from which it is discharged in any suitable manner after passing through the cooling jackets. The cam Q is releasably or retractably held by the spring U so that the pump will not be broke s'.ould it freeze up in cold weather. I l i The foregoing constitutes a conventional outboard motor )assembly upon which my invention -is employed, and I provide therefor 'a housing or duct member IIJ of tubular form having its opposite ends anged asA at III and I2. The upper flanged end II yis mounted by a screw I3 I4 formed in the rear portion of the unit G above the propeller shaft and drive connections, and is so arranged that the hous-l ing I0 will communicate with the interior of the standard B as shown. The lower flanged end I2 of the housing Ill is then secured by a screw I5 over `an opening I6 in the upper side of the rear portion of the unit G when it surrounds the propeller shaft J, so that the housing communicates with the op`en rear end of the unit. The

housing is curved, as shown, in order to clear the pump O, and is formed of a rearwardly tapering or aerofoil cross section as shown in Fig. 3, in order to reduce water resistance and drag. -A seal is formed at I1 (at its upper anged end) with the unit G and a shoulder I8 engages the pump O, all of which assembly devices aid in properly locating and sealing the housing IIJ in its connection with the transmission unit.

An anti-cavitation plate -I9 is formed on the unit G and its rearward portion I9a is carried by the housing I0 to extend rearwardly over the propeller 20 for the usual purpose. Of course the entire assembly is streamlined and shaped to reduce resistance to its travel through the fashion on the boat. The motor may and extended in a fore and.

water, and to facilitate plete scavenging in the steering of the boat to which the motor is attached.

The propeller 20 is of novel form in that it has the hollow trunco-conical hub ,2l by which it is secured on the rear extremity of the propeller shaft J. This hub 2| has its larger open end turned forwardly and fitted rotatably over the open rear end of the transmission unit G, as indicated at 22, and openings or vents 23 are formed in the hub between the blades 24. The propeller is secured to the shaft J by the usual lock nut 25. i

In operation the exhaust gases from the motor A are admitted to the upper end of the standard B in usual manner, and they iiow downwardly through said member in the space existing therein around the drive shaft H, emerging from the opening I4. Ordinarily the gases are simply discharged at whatever location is convenient, but, for purpose of exhaust lnoise reduction, it is of course 'desirable to discharge the gases below the water level. However, this has heretofore led' to 'difficulty due to the building up of back pressure in the exhaust system causing -incommotor, and also the noise has been but slightly reduced. By the use of my invention as described, the. gases are, however, now carried through the housing I0 and are discharged through the vents 23 out rearwardly of the hub of the propeller. Several advantageous actions now occur.` It will be readily understood that the action of the propeller `A I claim as new and desire mediately surrounding `the propeller to be urged outwardly and, so some extent rearwardly from the blades. There results, then, the formation of at least a partial vacuum immediately to the rear of the propeller hub 2|, and the exhaust gases emerging from the vents Z3 flow into this relative vacuum. The action is such that the gases are in effect sucked from the hub with such force and rapidity that ver'y complete scavenging will occur. Furthermore, the gases as they escape are co-mingled with the very turbulent water rearwardly of the propeller and are broken up to such extent that the exhaust noise is substantially eliminated, as will be evident.

In lieu of the propeller construction as just described, I may employ a propeller such as indicated'at 2|.'Ia in'-Fig. 4, where the hub 2 In is hollow tubular and open' and substantially cylindrical or from front to rear ends. The shaft J is then secured by the nut 25a in a smaller bearing 26 which is supported concentrically in the hub 2l by radially extendedand angularly turned fan blades 21 which extend between the hub and bearing inside of the former. This type of propeller, when rotating, sets up a positive and powerful suction through its hub by action of the blades 21, such as will very forcefully draw out the exhaust gases and discharge them rearwardly from the hub. ThisA action, supplemented as it is by the aforementioned vacuum formed behind the propeller hub, will positively scavenge the motor of all exhaust gases under all conditions.

It is understood that I may vary from the specic structures disclosed, provided that such variations fall within the spirit and scope of the appended claims.

Having thus fully disclosed my invention, what to secure by Letters Patent, is:

1. A boat propulsion apparatus comprism g, an internal combustion motor, a propeller driven by the motor and includingV a hollow hub member, blower fan blades in the said hub, and means for conducting exhaust gases from the motor to the hub whereby said gases will be discharged rearwardly through the hub by action of the blades therein.

2. A boat propulsion apparatus comprising, an internal combustion motor assembly including a housing member opening rearwardly and carry.

ing exhaust gases from the motor, a propeller driven by the motor and'having a hollow hub member rotating adjacent the said opening, and blower means in the said hub member for drawing the gases from the housing member and discharging vthem rearwardly from the propeller hub.

3. In a boat propulsion apparatus, a motor driven shaft of solid construction, a propeller.

- having a hub mounted on the shaft for rotation thereby, means for conducting waste products of the motor to a point forwardly of the hub but radially outwardly of the shaft, and the said hub having a passage opening forwardly to receive said products and opening rearwardly for the disand having a passageway outwardly thereof forthe discharge of waste products from the motor, and propelling means in said passageway for acting on said products to facilitate their movement therethrough.

5. In a boat propulsion apparatus, means for mounting a propeller shaft on the boat, an internal combustion engine for driving the shaft, a propeller mounted on the shaft to be driven thereby and including a chambered hub having vents opening rearwardly from the chamber, and means for delivering waste products of the motor rearwardly into the chambered hub but radially outwardly o f the'shaft, whereby said products may be discharged through the hub vents into the water acted upon byl the propeller.

ADOLPH RONNING. 

